1. Technical Field
Methods and apparatuses of the exemplary embodiments relate to a method and apparatus for encoding and decoding an image by using an adaptive search range decision for motion estimation.
2. Description of the Related Art
An image encoding apparatus compresses and encodes an original image, and an image decoding apparatus decompresses the compressed image.
The image encoding apparatus uses a method to remove a redundant element from image data to be transmitted to the image decoding apparatus. An estimation operation is used to remove a redundant element from the image data. In a motion estimation operation, a reference frame is searched to find a predictive block having a value nearest to a current block, and then information related to a difference between the predictive block and the current block is encoded.
In a related art motion estimation operation, a search range having a certain value is set in a reference frame, which is a frame previous to a frame including a current block. The search range has a fixed size, irrespective of a motion change of an image.
Therefore, in an image where a motion change is large, the motion change cannot be reflected in response to setting the search range. For this reason, a predictive block of a current block cannot be accurately determined, and thus, the image quality of image data transmitted to an image decoding apparatus is low.